40 



THE GEAPE ROOT-WORM. 



Table XVII. — Time of transformation of larvse and pupx of the grape root-worm in 

 the field, as observed in the vicinity of North East, Pa., 1909. 



Vineyard. 



Date 

 exam- 

 ined. 



Number 

 of vines 

 exam- 

 ined. 



Number 

 of larvae. 



Number 

 of pupae. 



Number 

 of beetles 

 in cells. 



J. D. Curtis's 

 vineyard, 

 porous silt. 



June 12 

 June 21 

 June 25 

 June 30 

 July 6 

 July 10 





286 

 6 

 2 

 2 



32 

 47 

 54 



4 





7 

 6 

 6 

 6 

 6 





2 



24 

 4 













G.E.Pierce's 

 vineyard, 

 gravel soil. 



June 11 

 June 21 

 June 25 

 June 30 

 July 6 

 July 10 





101 

 5 

 5 



49 

 13 

 12 





6 

 6 

 6 



7 

 6 







3 

 2 

















V ineyard, 

 1 o a m. y 

 soil. 



June 23 

 June 25 

 June 30 

 ■Tuly 7 

 July 10 

 July 17 



6 

 6 

 6 

 6 

 6 

 6 



3 



I 



1 



24 

 5 



17 

 2 



1 







2 

 2 

 1 











Whitman's 

 V i n e V ard, 

 clay soil. 



June 23 

 June 25 

 June 30 

 July 7 

 July 10 

 July 17 

 July 26 



6 

 6 

 6 

 6 

 6 

 6 

 6 



1 

 1 

 1 

 1 



6 

 5 

 2 









1 



1 





1 













It is possible to establish the time of pupation by knowing the time 

 of emergence of the beetle and the length of time of the pupal stage. 

 Judging by the late emergence of the beetles, August 9, and by the 

 finding of beetles in cells in the field August 14, pupse must have 

 occurred up to the end of July. Based upon these records the curve 

 of figure 23 has been constructed. 



DURATION OF THE PUPAL PERIOD. 



The pupal stage on an average lasts 17 days (see Tables XV and 

 XVI). The maximum length of time observed was 21 days and the 

 minimum 12 days. 



LIFE CYCLE OF THE GRAPE ROOT-WORM AS DETERMINED BY 



REARING. 



Several attempts were made to rear this insect from eggs, and to 

 carry it through the different stages to complete the life cycle. In 

 the course of these experiments many failures occurred. The mor- 

 tality in certain experiments was high; in other instances a large per- 

 centage became materially delayed in development and the larvae 

 wintered a second season, and only a small number completed the 

 life cycle within one year. (See Table XX.) The records from these 

 latter observations are given in Table XVIII, with dates of hatching 

 in 1908 and the dates of reaching maturity the following year. 



